The following table gives the frequency distribution of the times (in minutes) that 50 commuter students at a large university spent looking for parking spaces on the first day of classes in the fall semester of 2012.
Time Number of Students
0 to less than 4............ 1
4 to less than 8............ 7
8 to less than 12........... 15
12 to less than 16............ 18
16 to less than 20............ 6
20 to less than 24............ 3
Find the mean, variance, and standard deviation. Are the values of these summary measures population parameters or sample statistics?